2018 Mazda 3 to use compression ignition for 30 per cent efficiency boost | report

13 January 2017
 by 
, CarsGuide

Mazda’s next-generation SkyActiv petrol engine is expected to slash fuel consumption figures by another 30 per cent by ditching spark plugs.

It has been six years since Mazda adopted their SkyActiv suite of fuel efficient technologies, and it seems that they are preparing to up the ante with a new-generation of SkyActiv technologies. According to a report from the Nikkei Asian Review, Mazda will be introducing a new petrol engine at the end of next year in the facelifted Mazda3 that boasts a 30 per cent improvement in fuel efficiency. 

Based on current estimates, the new engine in the Mazda3 will be able to deliver a fuel consumption figure that is close to 3.3L/100km. By comparison, the best official combined figure achieved by the current 3 is 5.7L/100km, while even the Toyota Prius carries a 3.4L/100km rating. 

The new petrol engine, which is described to be part of the company’s second-generation SkyActiv suite of technologies, is said to operate on a new form of combustion that does away with spark plugs and ignites the fuel using the engine’s compression to achieve a more efficient combustion instead - similar in practice to that of a diesel engine.

Mazda’s engineers has also hinted that HCCI combustion serves as a key development to enable the return of the rotary engine.

This form of internal combustion is known as HCCI (homogeneous charge compression ignition), and Mazda says their new engine will be the first practical application of the technology should it be ready by the target date mentioned in the report. 

In theory, HCCI combustion is very similar to knocking or pinging (when unburnt fuel spontaneously ignites due to excessive heat and pressure before the combustion cycle takes place), though in the case of the HCCI the combustion is supposed to be intentional and controlled. 

Not only does HCCI achieves a leaner burn, it is also said to produce less exhaust emissions, particularly when it comes to the notorious NOx emissions, which would enable such engines to pass future emission regulations. 

Since combustion is achieved through pressure and heat, rather than spark ignition, commercialising HCCI engines has been difficult with several issues that need addressing such as cold starting, and more importantly, potential higher engine wear.  

That being said, due to its efficiency and cleaner emissions, HCCI combustion has been pursued by numerous manufacturers, most notably Mercedes-Benz which rolled out the F700 Concept with a HCCI engine back in 2007, though none has been able to deliver a production-ready engine so far. 

HCCI has been part of Mazda’s development plan for their SkyActiv range of engines, with the technology expected to make its debut in the company’s second-generation of SkyActiv engines. As previously reported, Mazda’s engineers have also hinted that HCCI combustion serves as a key development to enable the return of the rotary engine with its efficient combustion and the absence of a spark plug. 

For now Mazda Australia has no comment on the report, citing that at this stage it is too early to tell if and when a HCCI SkyActiv engine will be available for commercial sale, nor if the engine will make its debut in the facelift Mazda3 as stated in the report.

Is compression ignition a new lease on life for the internal combustion engine? Tell us what you think in the comments below.

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